Vacuum tube



Feb, '2. 1928*, 1,658,653

M. RENNER VACUUM TUBE Filed April 21, 192'? Inventov: michael Renner,

His Attorney.

Patented Feb. 7, 1928.

UNITED STATES PATENT OFFICE.

MICHAEL Brennan, or" SGOTIA, NEW YORK. AssIGNon T GENERAL ELECTRIC oom-PANY, a oonrona rrolv on NEW YORK.

VACUUM TUBE.

The present invention relates to vacuum tubes and more particularly tosuspenslon means 'for supporting the cathode element in such tubes. Oneof the objects of the inven- 6 tion is to provide a resilient cathodesupport which is so mounted in the vacuum tube that lateral movement ofthe cathode is prevented.

In the construction of vacuum tubes the amount of space between thecathode or filamentary electrode and the grid or control electrode isvery limited and it sometimes happens thatwhen the filament is heated orsubjected to vibration it will contact w1th the grid and therebyinterfere with the op eration of the tube. Heretofore, it has beenproposed to provide a suspension element for the filament whichcomprises a w1reextending through a rigidly supported insulator, one endof the suspension element being provided with a hook adapted to engagethe filament, and the other end of the suspension means being engaged bya spring supported on the insulator. As thns arranged, however, theopening 1n the nsulator has to be made quite large to provide for freemovement of the suspension means under all conditions and especiallywhen the filament is heated. Making the opening 1n the insulatorsufliciently large to provide for free movement of the suspension meanspermits the suspension means to pivot about the opening in the insulatorand thereby allow suflicient lateral movement of the filament to shortcircuit the filament on the grid. Ac.-

cording to the present invention this pivoting movement of thesuspenslon means has been prevented by the presence of a secondinsulator spaced from the first insulator and provided with meansthereby efiectively preventing lateral movement of the suspension meansand cathode.

The novel features which I believe to be characteristic of my inventionare set forth with particularity in the appended claims. My inventionitself, however, will best be pnderstood from reference to the follow ngspecification when considered n cgnnect on with the accompanying drawingin which Fig- 1 shows a front elevation artlybroken away of a vacuumtube embo ying the teatures of m invention while F1gs. 2. and 3 arerespectively a perspectivedetailed view an opening adapted ,to slid- 40ably engage the upper end of the suspension and a cross sectionaldetailed view of the means for supporting the filamentary cathode, Fig.3 being on a somewhat enlarged scale. y

Referring to-the drawing, I have indicated at 1 a vacuum tube of wellknown construction in which the anode 2 is supported on a split metalcollar 3 mounted at one end of the tube while the filamentary cathodeand grid are supported from the opposite end of the tube. An insulator 4is mounted on. the collar 3 and is provided with openings 5 adapted toaccommodate rods 6 which serve as a support for the grid or controlelectrode. Engagement of the rods 6 in these openings prevents lateralmovement between the anode and control electrode. A second insulator 7is mounted on rods 6 and held in position by small metal beads or othersuitable means. Insulator 7 is provided with a plurality of open ngs 8adapted to slidably accommodate suspension wires 9 each of which has ahook 10 at its lower end adapted to engage a filamentary cathode 11. A'

metal plate 12 having a downwardly extending flange 13 is rigidlysecured to wire 9 by means of a perforated plate 14 which is v welded towire 9 and plate 12. A second metal plate 15 restson insulator 7 andfits loosely on wire 9. Plate 15 is provided with r an upwardlyextending flange 16 as clearly indicated in Fig. 3. A cylindrical spring17 is mounted betwe'en'plates 12 and 15 and is normally held compressedby the tension of the filament 11. The flanged plate 15 prevents lateralmovement of spring 17 and holds it in central position with respect towire 9.

A third insulator 18 mounted on rod 6 and disposedbetween insulators 4and 7 is normally spaced from'the latter by a plurality of metal collarsor sleeves 19 mounted on rod 6. Metal beads 20 serve to maintaininsulator 18 in spaced relation with insulator 4. Insulator 18 isprovided-with a plurality of openings 21 in alignment with openings 8 ininsulator 7 and adapted to accommodate wires 9.

(The spacing collars 19 are of such alength' that the maximum upwardmovement ofthe plate 12 due to expansion of the filament when heated,will carry the plate to a point just short of insulator 18. The distancebetween insulators 4 and 7' is sufiicient to permit maximum upwardmovement of wire 9 sulator 4.

Spring 17 on account of its cylindrical shape and the bearings providedby the plates 12 and 13 causes movement of the wire 9 in a substantiallyvertical direction and thereby tends to prevent binding of Wire 9 in theopenings 8 and 21. However, if there is any tendency for lateralmovement of the lower end of wire 9, such movement is effectivelyprevented by the engagement of the upper end of this wire with the sidesof the opening 21 in insulator 18.

What I claim as new and desire to secure by Letters Patent of theUnitedStates is:

1. In an electric discharge device, a rigidly mounted insulator providedwith an opening, a wire extending therethrough, said wire having meansat its lower end adapted to engage a filamentary electrode, flexiblemeans engaging said wire whereby a. tension may be applied to 'thefilament, and means slidably engaging the upper end of said wire andadapted to limit lateral movement of said filamentary electrode.

2. In an electric discharge device, a pair of rigidly mounted insulatorsspaced apart from one another and provided with aligned openings, 0.wire extending through said without causing contact of wire 9 with in-vopenings, a wire extending through openings and adapted to engage thecathode openings and adapted to engage a filamentary electrode, and'aspring mounted between said insulators and connected to said wire.

3. In an electric discharge device, a pair of rigidly mounted insulatorsspaced apart from one another and provided with aligneg element of thedischarge device, a plate rigidly connected to said wire, and a springmounted between said plate and one of said insulators.

4. In an electric discharge device, a rigidly mounted insulator havingan opening extending therethrough, a plate having an opening inalignment with the opening in the insulator, said plate having anupwardly extending flange, a wire extending through said openings, saidwire having a hook at its lower end adapted to engage a filament, aplate having a downwardly extending flange rigidly secured to said wireadjacent the upper end thereof, and a substantially cylindrical springmounted between said plates and adapted to apply tension to thefilament.

In witness whereof, I have hereunto set my hand this 20th day of April,1927.

MICHAEL RENNER.

